The second choice is puncuted correctly.
C. Metaphor
The author is trying to say Cruel words can hurt people, the author is comparing cruel words with weapons, he is making a figure of speech, 'Cruel Words Are Weapons' is a figure of speech (Metaphor),So that makes C. Metaphor correct.
Hope this helps! :)
My best friend loves to laugh.
When I laugh, my stomach hurts.
His laugh makes him sound like a hyena.
Think along these lines :)